This invention relates to an electrical musical instrument having a circuit for automatically playing notes chordally related to a manually selected root note.
The relatively recent popularity of electrical musical instruments, such as electronic organs, is due in great part to automatic features thereof which enable an inexperienced organist to achieve musical effects which could not otherwise be achieved. One such musical effect that inexperienced organists find difficult to perform is a walking bass effect. In the walking bass effect, bass notes chordally related to a root note of a chord selected on an accompaniment keyboard are rhythmically played on the pedal clavier. Alternately, a walking bass effect is achieved by rhythmically playing notes chordally related to a root note selected on the pedal clavier, when no note selections are being made on the accompaniment manual.
Circuits for automatically achieving these effects are known. In U.S. Pat. No. 3,548,066 issued Dec. 15, 1970, to Freeman, a circuit is shown having one mode of operation in which the root and fifth parts of a chord selected on the accompaniment manual are automatically rhythmically sounded in the bass. In another mode of operation, the root and fifth parts are sounded in the bass in response to root note selections on the pedal clavier. The Freeman circuit achieves this result through inhibiting and enabling circuit links for controlling various keyers associated with the bass notes, and is limited to sounding only the root and fifth parts. Other parts of the chord, such as the third, seventh, etc., cannot be automatically generated.
Another approach to automatic generation of the notes of a chord is shown in the co-pending U.S. application of Carlson Ser. No. 482,064 filed June 24, 1974, now U.S. Pat. No. 4,019,417, issued April 26, 1977, and assigned to the assignee of the present invention. There, all the tone signals of a selected chord are generated in response to detection of a root note selected on the keyboard. The generated tone signals are provided to a sequential gating circuit which sequentially gates, one at a time, selected ones of the generated tone signals to voicing circuitry.
In U.S. Pat No. 3,544,693 issued Dec. 1, 1970, to Tripp, a pedal root tone is selected and all of the tones of the chord of that root are developed in response thereto. Selected ones of the provided tones are then sounded in accordance with a separate selection of the type of chord to be played.
A different approach to automatic note generation is shown in the U.S. Pat. No. 3,610,801 issued Oct. 5, 1971 to Fredkin. A digital musical synthesizer is shown there in which digital note information is stored in a shift register 15 and periodically changed through digital feedback signals from different points in the register itself to thereby successively provide information representative of different notes.